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ALLone



Joined: 21 Apr 2007
Posts: 1

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PostPosted: Thu Oct 11, 2007 3:00 pm     Reply with quote
Hi.
I use version 4.023 and have a problem with cpp.(i think)
Quote:
#include <16F877.h>
#device adc=8

#FUSES NOWDT //No Watch Dog Timer
#FUSES XT //Crystal osc <= 4mhz
#FUSES NOPUT //No Power Up Timer
#FUSES NOPROTECT //Code not protected from reading
#FUSES BROWNOUT //Reset when brownout detected
#FUSES LVP //Low Voltage Programming on B3(PIC16) or B5(PIC18)
#FUSES NOCPD //No EE protection
#FUSES NOWRT //Program memory not write protected
#FUSES NODEBUG //No Debug mode for ICD

#use delay(clock=4000000)
#include <stdlib.h>
//*****************************************************************************
int tim=1;
int16 ccp1_buf,ccp2_buf;
//*****************************************************************************
#int_RTCC
void RTCC_isr()
{
tim++;

if (tim==20)
{
output_high(PIN_C1);
output_high(PIN_C2);
setup_ccp1(CCP_COMPARE_CLR_ON_MATCH);
setup_ccp2(CCP_COMPARE_CLR_ON_MATCH);

CCP_1=ccp1_buf;
CCP_2=ccp2_buf;
set_timer1(0);
tim=0;

return;
}
if (tim==2)
{setup_ccp1(ccp_off);
setup_ccp2(ccp_off);
set_timer0(130);
return;}

}
//****************************************************************************
void main()
{

setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_psp(PSP_DISABLED);
setup_spi(FALSE);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_4);
setup_timer_1(T1_INTERNAL|T1_DIV_BY_1);
setup_timer_2(T2_DISABLED,0,1);

ccp2_buf=1500;
ccp1_buf=1500;

enable_interrupts(INT_RTCC);
enable_interrupts(GLOBAL);


while(1)
{

}

}

When i compilied this code there no error. But the ccp1 and ccp2 pin only high for 1-2 us instead of 1.5 ms. Can you help with the code pls?
Kenny



Joined: 07 Sep 2003
Posts: 173
Location: Australia

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PostPosted: Thu Oct 11, 2007 10:36 pm     Reply with quote
The CCP output latch is never set high!
The CCP latch is not the data latch. What is happening is that the the output pin is being set high by output_high() then immediately pulled low by setup_ccpx(CCP_COMPARE_CLR_ON_MATCH) because the default state of the CCP latch is low.

Don't switch between CCP mode and data mode.
Delete setup_ccpx(ccp_off);

Then to set the pin high, instead of output_high() use the technique shown in the CCS example EX_CCP1S.C

setup_ccp1(CCP_COMPARE_SET_ON_MATCH); // Configure CCP1 to set
CCP_1 = 0;
set_timer1(0); // C2 high now
Guest
PostPosted: Fri Oct 12, 2007 6:48 am     Reply with quote
thank you very much.. Now it's working properly.
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